New morphometric techniques, applied to the lung, allow quantification of normal and abnormal growth and development of the pulmonary vascular bed. In congenital heart defects, causing increased pulmonary blood flow, abnormal remodeling of the structure of the small arteries occurs, fetal musculature sometimes fails to regress, muscle extends into those peripheral arteries not normally muscular and there is additionl medial hypertrophy. Arteries do not multiply normally-they decrease both in number and in size. We have shown that these features can be analyzed on lung biopsy tissue taken at the time of surgical repair and they can be correlated with the preoperative level of pulmonary artery pressure and resistance. We now propose to analyze and quantify these new morphologic features on lung biopsy tissue in congenital heart defects causing increased pulmonary venous pressure in addition to those causing increased pulmonary blood flow and to establish their prognostic significance by correlaing their presence and severity with the level of pulmonary artery pressure and resistance one year after corrective surgery. In a small group of patients with congenital heart defects, microscopic morphologic abnormalities of pulmonary vascular growth and development seen on biopsy tissue correlate significantly with preoperative quantitative analysis of the rate of tapering of the right posterobasal segment axial pulmonary artery as seen on the pulmonary wedge angiogram. We now propose to extend and refine our technique so that wedge angiography can eventually be used to assess the morphologic state of the pulmonary vascular bed both pre and postoperatively without the need for lung biopsy. Finally, we plan to extend our methods of analysis to quantitative postmortem evaluation of the lungs in particular to the congenital heart defects which have not been adequately studied, such as those causing decreased pulmonary blood flow. Preliminary work shows an abnormal growth and development of the alveoli as well as of the arteries in the latter condition - a finding not typical of other defects.